[sdiy] Processing Midi - Dropping Notes

[phillip m gallo]

Theo,
 
Think you mis-understand.  I didn't/don't advise coding for a few
specific cases.   
 
Instead the entire MIDI Status set should be carefully considered, and
planned for, even in cases where you intend to do no more than drop the
message.
 
When using either method (buffered or on the fly), message sequencing
and traffic implications were where the real work in implementing,
seemed to lie.
 
Haven't seen the MMA flows will give them a look, thanks for the ref.

 
regards,
p
 
 
-----Original Message-----
From: Theo [mailto:t.hogers at home.nl] 
Sent: Friday, July 16, 2004 3:47 PM
To: philgallo at attglobal.net
Cc: synth diy
Subject: Re: [sdiy] Processing Midi - Dropping Notes


Agreed it was just a example, however a valid example, its allowed and
may occur.
For fail save midi reception you need to use a method similar to the one
I described before using a running "status buffer" and "first data byte
flag" + "first data byte buffer".
The method I described in the first mail automatically takes care of all
possible midi input including sysex, running status and realtime
messages.
BTW the MMA has flow diagrams for midi reception, all are variations of
this same method.
 
To rely on just a few specific situations like you suggested is not the
preferred design.
 
Theo
 
 
 

----- Original Message ----- 
From: phillip  <mailto:philgallo at attglobal.net> m gallo 
To: 'Theo' <mailto:t.hogers at home.nl>  
Cc: synth diy <mailto:synth-diy at dropmix.xs4all.nl>  
Sent: Friday, July 16, 2004 10:34 PM
Subject: RE: [sdiy] Processing Midi - Dropping Notes

Theo,
 
The issuance of a Note On message should preclude the need for an Active
Sense  message.   I have no doubt that folks violate the intent of
Active Sensing by tying it to some blind timer based routine, but Active
Sensing is intended to occur when there is no other traffic that would
indicate the MIDI link is "in service".
 
regards,
p
 
-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Theo
Sent: Friday, July 16, 2004 1:22 PM
To: synth-diy at dropmix.xs4all.nl; David Brown
Subject: Re: [sdiy] Processing Midi - Dropping Notes


Hi David,
 
Yes real-time messages can replace expected data just like the example
you gave.
Yes the real time message is guaranteed to be one byte only, but more
than one real-time message is possible.
 
Like:
Note on
Note value
Real-time active sensing 
Real-time timing clock
Note velocity
 
Or:

Note on
Real-time active sensing 
Note value
Real-time timing clock
Note velocity
 
The real time messages are:
$F8 - Timing clock
$F9 - undefined
$FA - start
$FB - continue
$FC - stop
$FD - undefined
$FE - active sensing
$FF - system reset
 
The other one byte messages ($F1...$F7) are not real-time and not
allowed to go in-between the data of other messages.
However I like to pars them as if they where real-time messages, part
for easy of coding.
But also because of timing.
"Midi time code quarter frame" ($F1) is one of them, you don't like that
one waiting in a FIFO too long.
And having "Song select"($F3) or "Song position pointer"($F2) waiting in
the FIFO while $FA "start" is received and executed in is also a bit
sloppy.
 
Best use a method that takes care of these things automatically.
Like the one I described in the other message.
 
Cheers,
Theo
 
 
 

----- Original Message ----- 
From: David  <mailto:davebr at earthlink.net> Brown 
To: synth-diy at dropmix.xs4all.nl 
Sent: Friday, July 16, 2004 6:14 PM
Subject: Re: [sdiy] Processing Midi - Dropping Notes

At 09:34 PM 7/13/2004, you wrote:


For even more fun there is also "real time messages" that can come
in-between the bytes of other messages.
 
The real time messages are one byte only.
So just check if a message is real time, then do something with it, like
nothing at all.


Can you clarify the real time messages?  I'm writing my own MIDI parser
and I don't know if I have handled it correctly.  Specifically, can a
real time message replace the expected data in a message?  For example
...

Note on command
Note value
Real time message
Note velocity

In this case, is the real time message always guaranteed to be one byte?

Thanks. - Dave 

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